Fake Friends?

I feel like no one talks about the friends who you'll talk at school and meet in hallways and such but the minute something actually happens in your life they don't bother even texting you asking about what happened or where you went. But the minute you go back to school their all-buddy buddy with you. are these fake friends, or no? I'm only confused because I recently like actually thought it over and I don't know because originally the thought of fake friends are people who talk behind your back or acts all nice in front of you then switches up or something like that. But would that be considered fake friends. PS: the people I am talking about they have multiple ways of contacting me okay. but Lokey i really do want to get another person's input or even their view on the situation. 

Byeee My Loveleys!!!  <3